How to simulate the function realloc in C++

[tiredoy]

Dear friends,
These days ,I am learning something related to linear list.In implmenting the function of realloc.I have been pullzed for several days,although I can use "include" method to directly use the function.
However , I　deeply wonder that how can I write my own code to solve such questions in c++.
Willing to receive yours help.
Thanks a lot.
-------------------tiredoy

[tiredoy]

#include<iostream>
#include"malloc.h"
using namespace std;

class myList{
public:
	int* list;
	int size;
	
	
	
};

class LList
{
private:
	int Size;//index value that represents the exist data.
	int OldSize;
	int MaxSize;
	int StepIncrz;
	myList* myll;
public:
	void Remalloc()
	{
		myList* newptr;
		OldSize=MaxSize;
		MaxSize+=StepIncrz;


		newptr->list=new int[MaxSize];

		//copy old to new 
		for(int i=0;i<OldSize;++i)
		{newptr->list[i]=myll->list[i];}
		myll=newptr;
	
	};
	LList()
	{
		Size=0;
		StepIncrz=30;
		myll->list=new int[10];
		MaxSize=10;
		
	};
	bool CheckFull()
	{return (Size>=MaxSize);};
	void addValue(int data)
	{
		if(CheckFull())
		{
			Remalloc();
		
		}
		myll->list[Size]=data;
		++Size;
	
	};
	int GetData(int position)
	{
		if(position >=Size)
		{
			cout<<"Error!";
			return 0;}
		else {
			return myll->list[position];
		
		
		}
	
	
	}



};

void main()
{
	LList a;
	a.addValue(3);
	a.addValue(5);
	a.addValue(44);
	a.addValue(23);
	a.addValue(12);
	a.addValue(56);


	for(int j=0;j<=5;++j)
	{cout<<a.GetData(j);}



}